This invention relates to articles made of clay and, more particularly, to fired clay articles. In another aspect this invention relates to consolidated structural articles.
Since clay can be made plastic by addition of water, easily worked into various shapes by hand, and then fired to a rigid and water-insoluble state, clay has accordingly been used for centuries by even the most primitive civilizations to make pottery, building blocks (e.g., bricks), jewelry, tools, etc. Because clay is so easily worked and because it is a very common material -- it being found in virtually every country and locality -- its use has been extremely wide-spread. In fact, in some countries clay is virtually the only material available which can be used economically to make houses and other building structures. Because of this widespread and extensive use of clay, the art of making it plastic with water, shaping it into a desired article, and then drying and firing the article has become highly developed and well-known throughout the world.
In one aspect the present invention provides unique articles in the form of small hollow pillows which can be easily formed from conventional clay and then fired. The pillows can be readily and economically bound together in any desired configuration to form rigid but light-weight consolidated structures or articles useful, for example, in the construction of buildings. The consolidated pillow structure has a high degree of void space between pillows, is self-supporting and load bearing, is easily worked with common tools, may be reinforced in conventional manners, and has a low coefficient of thermal expansion and contraction. It also has other very desirable properties including fire-resistance, vermin-resistance, weather-resistance (i.e., it does not deteriorate under the effects of freeze-thaw cycling, sunlight exposure, is practically water-insensitive), good sound absorption, ventilation and thermal insulation properties. The consolidated structures may be easily and conveniently made to any desired size and shape at the time of use without any waste of material.
Consequently, the consolidated structures of the invention are a marked improvement over conventional clay, ceramic and concrete building materials such as bricks, blocks and building tile which are heavier, non-insulative, must be bonded together with mortar, difficult to cut to desired size and shape, requires skilled labor for assembly, are expensive to transport, and cannot practicably be preassembled off the job site.
Since any conventional clay may be used in the practice of this invention, and since clay is a plentiful natural resource in all countries, the present invention provides a simple and economical solution to the construction industry in countries which are beset with lack of conventional building materials or financial ability to procure such materials.
Although others have made consolidated structures using particles of various shapes and designs bonded together, such prior art structures have inherent disadvantages of one type or another and have not been found useful in the areas of application where the present invention provides unique advantages. For example, rocks or stones of various shapes and sizes have previously been bonded together with resinous binders (e.g., Hensley, U.S. Pat. No. 3,687,021) or with asphaltic binders (e.g., Richards, U.S. Pat. No. 3,439,450). However, the disadvantages inherent in those structures include high bulk density (e.g., about 100 pounds per cubic foot, or more), low insulative properties, only a low to moderate degree of void space, have very limited self-supporting characteristics, and are virtually unworkable with common tools. Furthermore, the amount of binder which must be used in consolidated rock structures is substantial because of the numerous large contact areas between rock surfaces.
Other consolidated structures made of wood, plastic, and the like typically are not suitable or desirable as structural elements nor can they be conveniently made to the desired size and configuration. In any event, such structures do not offer the myriad of unique advantages and practical features provided by the present invention.